Tithonian

The Tithonian is a special time period in Earth's history, part of what scientists call the Late Jurassic Epoch. It was the last age of this time and came right before the Cretaceous period began. If you imagine the Earth’s timeline like a very long book, the Tithonian would be one of the last chapters in the Jurassic section.

This period lasted from about 149.2 million years ago to 143.1 million years ago. It came after another stage called the Kimmeridgian and was followed by the Berriasian stage, which is the first part of the Cretaceous. Many famous dinosaurs, like Allosaurus and Brachiosaurus, lived during this amazing time when the world was very different from today.

Stratigraphic definitions

The Tithonian was named by a scientist named Albert Oppel in 1865. Its name comes from Greek mythology, after Tithonus, who fell in love with the goddess of dawn. This stage marks a time period long ago in Earth's history.

The Tithonian is divided into early, middle, and late parts. It includes several layers identified by special fossils called ammonites, which help scientists study this ancient time.

Sedimentary environments

During the Tithonian, sedimentary rocks formed in the Tethys Ocean, including limestones that contain fossils. One famous example is the Solnhofen limestone from southern Germany, which is known for its well-preserved fossils, especially Archaeopteryx.

Tithonian extinction

The later part of the Tithonian stage saw an extinction event known as the Tithonian extinction. This event was fairly minor and selective, ranking outside the top 10 largest extinctions since the Cambrian. However, it was still one of the largest extinctions of the Jurassic Period.

Scientists have several ideas about what caused this extinction. One theory suggests that the extinction was due to habitat loss from a major sea level fall, which would have affected marine life especially in Europe. Another idea is that volcanic activity or asteroid impacts may have played a role, though these events were likely more localized. Some researchers also think that the appearance of fewer fossils from this time might make it seem like there was an extinction when it might just be a problem with how we search for and find fossils.

This extinction affected many types of animals. In the oceans, some groups of marine reptiles, like thalassochelydians and certain plesiosaurs, were strongly impacted. On land, sauropod dinosaurs, such as diplodocids and mamenchisaurids, saw significant reductions in diversity. Other groups, like rebbachisaurids and turiasaurs, managed to survive and even expanded later. Overall, the Tithonian extinction marked important changes in both marine and land ecosystems as some species declined and others began to diversify.